Cool Tech from 1982: The Prophet 600

I think it's natural to be interested in the state of technological progress, the state of the world even, at the time of one's birth. To ask big questions like "how did anyone survive?", "what did they do for fun?" and appraise the scope of development reaching back from now unto our baseline "year zero".

Despite such developments happening on a continuum - the restless pace of those seeking worth - a curious effect can appear: We develop a bias towards "our" year as the most inventive, the birth of a modern world, the year the world went from monochrome to colour.

I won't be challenging that bias - I think it's fairly benign as biases go - and well, it's my series of articles, so I'll be writing about all the cool stuff that changed our musical lives in 1982. There's a fairly staggering amount of "stuff" to get through, so let's start with Sequential's Prophet 600.

A Lesser Prophet

The story of San Francisco-based Sequential Circuits is well known. Founded by industry icon Dave Smith in 1974, Sequential initially offered innovative gadgets like the SCI 700 Programmer - a way of adding 64 patch memories/programmable envelopes to any CV-controlled synth. In 1978 their motherlode appeared - the Prophet 5.

The Prophet 5 introduced the world to the modern polysynth. It was fully programmable with 40 preset memories (not that most owners ever changed them - 75% of repairs came in with the factory presets intact!) and a wide array of sound design features. It could do your pleasant, filtered saw/square/triangle sounds all day long, but flick a switch and tearing hard sync leads, aggressive "polymod" clangs and all sorts of weirdness sprang forth. The Prophet 5 has range - equally at home with John Carpenter as it is with Hall & Oates.

Originally retailing for over £3,000 - the price eventually dropped to a more reasonable £2,200 but, facing big competition from Japanese instrument makers, Sequential were prompted to think about a cost-reduced offering. In December 1982 - the same birth month as certain Sonic Talk panelist - the Prophet 600 appeared, keeping much of the Prophet 5's DNA at a bargain £1650. Gone was the button-laden Koa/Walnut chassis, replaced with black painted steel (goths will love it!) and a cheap membrane panel.

Internally, the Prophet 600 nearly halved the chip count, pairing big brother's CEM3340 oscillators with a number of CEM3372's that acted as both filter and amplifier. Other than a pair of CEM3360 VCA's for modulation, everything else was handled by another chip - a Zilog z80 CPU.

That poor z80 - used to a life of gentle, Sunday afternoon ZX BASIC coding - was put to work within the new Prophet. The chip handled key & knob scanning, LFO and envelope generation, plus the real-time sequencer. Many think it was over-worked, creating artefacts like envelopes with audible zipper noise, janky/steppy knob scanning or endless auto-tuning loops.

On these original, z80-powered 600's, I've actually had multiple reports that it's impossible to get all 12 VCO's (6 voices x 2 oscillators a piece) in tune at once! Still, I think the 600 stands today as a totally bleeding-edge product from a time where clever knowhow pushed tech to its absolute limits.

Crucially, the Prophet 600 was amongst the first instruments to have MIDI! It was bare bones - note on/off, pitch bend and program change, but that was enough to change music production forever. At the 1983 Winter NAMM show in Anaheim, California, a Prophet 600 and a Jupiter 6 - connected via a single MIDI cable - played in sync; a moment of triumph for the new, universal musical instrument protocol.

Gligli Firmware

And of course, these days we have the Teensy-based Gligli update; a CPU brain transplant where the z80 is swapped for a 21st century micro-controller. This has resulted in higher resolution envelopes with multiple curves, a high resolution LFO with increased range/more LFO shapes and an assortment of other goodies like:

• Dedicated vibrato LFO
• Unison detune
• Mix Overdrive
• Full MIDI CC control and velocity via external MIDI.

Given the code's open source nature; various firmware revisions and tweaks have been released over the years, some by community members like Imogen. Such work is testament to the 600's strong basic tone - the reason why, even as an imperfect machine, it takes a place on our Cool Tech from 1982 list.

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